Weight training is a common form of exercise to increase strength and build muscle. A typical weight lifting apparatus includes a bar that is capable of receiving weights on both ends. The user places the desired weights on the bar, and then lifts the bar so that the weights act as resistance to the muscles of the user. A certain number of repetitions of the lift are performed in order to complete a particular exercise. Typically, the most beneficial parts of the exercise are the last few repetitions where the user may become fatigued, but where maximum muscle strength is developed. Because of the fatigue factor, the user may become exhausted and unable to complete the exercise with the selected weights. This results in at least two problems. First, in order to complete the set of repetitions, if fatigue sets in, the user may be required to stop the exercise, change the weight resistance (which may include both removing and replacing weights), and then resume. This may interrupt critical timing in the exercise. Second, the fatigue experienced by the user is dangerous in that the weights may be dropped or mishandled, resulting in injury to the user. A second person or spotter is typically used to assist the weight lifter to catch the weight in case fatigue causes a problem. However, a second person is not always available which may expose the weight lifter to unnecessary risk of injury.
In order to avoid having to add and remove physical weights to change the resistance, numerous weightlifting systems have been developed as alternatives to bar and weight systems that employ cable and pulley systems to transfer weight loads, such as those described in U.S. Pat. No. 5,407,403 and U.S. Patent Application Publication No. 2005/0233871. In order to avoid the need for a second person to act as a spotter, cable and pulley systems have also been developed for use as spotter systems, such as those described in U.S. Pat. Nos. 5,048,826, 5,310,394, 5,314,394, and 6,558,299. Unfortunately, none of these inventions provides a simple, compact weight resistance system that has the combined capabilities of (a) providing variable adjustability in the amount of tension (weight) placed on the cable, including automatic tension adjustment (reduction or release) near the end of a set of repetitions when the user is becoming fatigued; and (b) providing an automatic spotting/safety function without the need for a second person.
Electronic monitoring and feedback systems for weightlifting have also been developed, as described in U.S. Pat. Nos. 5,785,632 and 5,993,356.
It is therefore desirable to provide the combined capabilities of variable and automatic tension adjustability, including reduction and potential release (spotting) in a compact tension resistance system that may be adapted for use in numerous different weight lifting methods and apparatus. It is further desirable that such systems provide real time feedback to the user during exercise, and record the results of the user's exercise for future use.